The present invention provides a regulated bi-directional DC-to-DC voltage converter. More particularly, a bi-directional DC-to-DC voltage converter having a regulated output, and capable of converting between a high-potential direct current voltage and a low-potential via a pulse-width modulation ("PWM") technique. Additionally, the disclosed invention accomplishes the voltage conversions with a minimal number of components, and therefore provides for a reliable converter which offers advantages in size and weight over prior art designs.
Regulated bi-directional DC-to-DC voltage converters are employed extensively in aerospace applications to provide a means of coupling batteries (typically a 28 volt arrangement of cells) and the high-voltage (typically 270 V) DC bus which provides power to the various flight systems. When in a "step-up" mode the converters function to increase the battery voltage level to the required high-voltage bus level, and when in an "step-down" mode, the converters reduce the high voltage available on the bus to a level suitable for battery charging.
As with most components intended for aerospace applications, the minimization of the size and weight of bi-directional voltage converters is of great concern. The primary contributors to both the size and weight of such a voltage converter are its transformer and inductors (the so-called "magnetic components"). As typical regulated bi-directional DC-to-DC voltage converters require at least two inductors (one on each side of the transformer) to be employed to decouple the rectifying and switching components of the converter from its DC capacitors, the impact of the magnetic components on the converter's size and weight is increased even further. Also of concern in an aerospace system is the reduction of electromagnetic interference ("EMI") generated by any component. Typically, power converters create EMI as a result of current switching performed during conversion.
Accordingly, it is the object of the present invention to provide a regulated bi-directional DC-to-DC voltage converter which employs a single transformer and a single inductor (thus reducing the size and weight of the converter), and which provides a stable output voltage level over a wide range of input voltage variation in either the step-up or step-down mode. In addition, the invention insures the minimization of generated EMI as it maintains a continuous input current during step-up operation.